php test task

Task.php

<?php

//    
//    //count(array_filter($this->getUsers(), fn($user) => $user['city_id'] === $cityId));

class Test
{
    /**
     * Example:
     *  [
     *      1 => 'Robert De Niro',
     *      2 => 'Leonardo DiCaprio',
     *      3 => 'Tom Hanks',
     *      4 => 'Angelina Jolie',
     *  ]
     *
     * @return array[]
     */
    public function getUserNamesMap(): array
    {
        $data = [];
        foreach ($this->getUsers() as $user) {
            $data[$user['id']] = $user['name'];
        }
        
        return $data;
    }

    /**
     * Example:
     *  [
     *      ['id' => 1, 'name' => 'Robert De Niro', 'city' => 'Lutsk'],
     *      ['id' => 2, 'name' => 'Leonardo DiCaprio', 'city' => 'Donetsk'],
     *      ['id' => 3, 'name' => 'Tom Hanks', 'city' => 'Lutsk'],
     *      ['id' => 4, 'name' => 'Angelina Jolie', 'city' => ''],
     *  ]
     *
     * @return array[]
     */
    public function getUsersInfo(): array
    {
        $getUsers = $this->getUsers();
        $getCities = $this->getCities();
        $getCitiesMap = [];

        foreach ($getCities as $city) {
            $getCitiesMap[$city['id']] = $city['name'];
        }
        
        
        foreach ($getUsers as $index => $user) {
            $getUsers[$index]['city'] = $getCitiesMap[$user['city_id']] ?? '';
            unset($getUsers[$index]['city_id']);
        }

        return $getUsers;
    }

    /**
     * Example:
     *  [
     *      'Lutsk' => 2,
     *      'Donetsk' => 1,
     *      'Kyiv' => 0,
     *  ]
     *
     * @return array[]
     */
    public function getPopulation(): array
    {
        $getCities = $this->getCities();
        $getUsers = $this->getUsers();
        $data = [];
        $population = [];

        foreach ($getUsers as $user) {
            $cityId = $user['city_id'];
            if (!isset($data[$cityId])) {
                $data[$cityId] = 1;
            } else {
                $data[$cityId]++;
            }
        }
        
        foreach ($getCities as $city) {
            $population[$city['name']] = $data[$city['id']] ?? 0;
        }
        
        return $population;
    }


    private function getUsers(): array
    {
        return [
            ['id' => 1, 'name' => 'Robert De Niro', 'city_id' => 1],
            ['id' => 2, 'name' => 'Leonardo DiCaprio', 'city_id' => 2],
            ['id' => 3, 'name' => 'Tom Hanks', 'city_id' => 1],
            ['id' => 4, 'name' => 'Angelina Jolie', 'city_id' => 3],
        ];
    }

    private function getCities(): array
    {
        return [
            ['id' => 1, 'name' => 'Lutsk'],
            ['id' => 2, 'name' => 'Donetsk'],
            ['id' => 4, 'name' => 'Kyiv'],
        ];
    }
}

$test = new Test();

echo 'UserNamesMap:' . PHP_EOL;
var_dump($test->getUserNamesMap());

echo 'UsersInfo:' . PHP_EOL;
var_dump($test->getUsersInfo());

echo 'Population:' . PHP_EOL;
var_dump($test->getPopulation());